title: 68Ga-DOTATOC PET/CT and somatostatin receptor (sst1-sst5) expression in normal human tissue: correlation of sst2 mRNA and SUVmax.
abstract: OBJECTIVE
  By targeting somatostatin receptors (sst) radiopeptides have been established for both diagnosis and therapy. For physiologically normal human tissues the study provides a normative database of maximum standardized uptake value (SUV(max)) and sst mRNA.
  
  
  METHODS
  A total of 120 patients were subjected to diagnostic (68)Ga-DOTATOC positron emission tomography (PET)/CT (age range 19-83 years). SUV(max) values were measured in physiologically normal tissues defined by normal morphology, absence of surgical intervention and absence of metastatic spread during clinical follow-up. Expression of sst subtypes (sst1-sst5) was measured independently in pooled adult normal human tissue by real-time reverse transcriptase polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  SUV(max) revealed a region-specific pattern (e.g., mean ± SD, spleen 31.1 ± 10.9, kidney 16.9 ± 5.3, liver 12.8 ± 3.6, stomach 7.0 ± 3.1, head of pancreas 6.2 ± 2.3, small bowel 4.8 ± 1.8, thyroid 4.7 ± 2.2, bone 3.9 ± 1.3, large bowel 2.9 ± 0.8, muscle 2.1 ± 0.5, parotid gland 1.9 ± 0.6, axillary lymph node 0.8 ± 0.3 and lung 0.7 ± 0.3). SUV(max) was age independent. Gender differences were evident within the thyroid (female/male: 3.7 ± 1.6/5.5 ± 2.4, p < 0.001; Mann-Whitney U test) and the pancreatic head (5.5 ± 1.9/6.9 ± 2.2, p < 0.001). The sst mRNA was widely expressed and heterogeneous, showing sst1 to be most abundant. SUV(max) values exclusively correlated with sst2 expression (r = 0.846, p < 0.001; Spearman rank correlation analysis), whereas there was no correlation of SUV(max) with the expression of the other four subtypes.
  
  
  CONCLUSIONS
  In normal human tissues (68)Ga-DOTATOC imaging has been related to the expression of sst2 at the level of mRNA. The novel normative database may improve diagnostics, monitoring and therapy of sst-expressing tumours or inflammation on a molecular basis.
authors.affiliation: Department of Nuclear Medicine, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany. christian.boy@uk-essen.de
authors.forename: Christian
authors.initials: C
authors.lastname: Boy
authors.forename: Till A
authors.initials: TA
authors.lastname: Heusner
authors.forename: Thorsten D
authors.initials: TD
authors.lastname: Poeppel
authors.forename: Anja
authors.initials: A
authors.lastname: Redmann-Bischofs
authors.forename: Nicole
authors.initials: N
authors.lastname: Unger
authors.forename: Walter
authors.initials: W
authors.lastname: Jentzen
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Brandau
authors.forename: Klaus
authors.initials: K
authors.lastname: Mann
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.forename: Andreas
authors.initials: A
authors.lastname: Bockisch
authors.forename: Stephan
authors.initials: S
authors.lastname: Petersenn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives*; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography / Q000592:standards*; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017481:Receptors, Somatostatin / Q000235:genetics*; D012016:Reference Values; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014057:Tomography, X-Ray Computed / Q000592:standards*; D055815:Young Adult
chemical_list: C499142:Ga(III)-DOTATOC; D009942:Organometallic Compounds; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; D015282:Octreotide